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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: damac on January 15, 2005, 03:10:56 PM

Title: converting alkanes to alkynes
Post by: damac on January 15, 2005, 03:10:56 PM

Hi guys i am doing a chemistry assignment and am stuck on two questions the first one is how do i convert 1,1-dibromobutane to 2-pentyne.  I have been having problems with this i have no problem converting an alkene to an alkyne but am having a problem with an alkane to alkyne.

And my second question is in regards to reaction energy diagrams.
I have scanned the question for you guys to take a look

if someone could help me out i would appreicate it.

Thanks again guys

Title: Re:converting alkanes to alkynes
Post by: Mitch on January 15, 2005, 04:23:43 PM

1.) Look in your organic text for elimination reactions, it should have a huge section on it.

Title: Re:converting alkanes to alkynes
Post by: damac on January 15, 2005, 06:20:27 PM

wouldnt an elimination reaction produce an alkene

Title: Re:converting alkanes to alkynes
Post by: Donaldson Tan on January 15, 2005, 06:28:42 PM

please scale your image file to less than 600X600 in future. regarding your thermodynamics question, keep in mind that G is a state variable, therefore its value is independent of the pathway, hence u can simply sum the values up for the two values of the standard and non-standard G.

for A->C,
non-standard deltaG = +53.4kJ/mol
standard deltaG = -21.5kJ/mol

for C->A,
non-standard deltaG = -53.4kJ/mol
standard deltaG = +21.5kJ/mol

for (c) & (d), you may quote from the given data.

Title: Re:converting alkanes to alkynes
Post by: dexangeles on January 16, 2005, 03:39:33 AM

There is an Elimination Reaction for dihalides whether they are geminal or vicinal.
in your case, it's a geminal dihalide
there also is a difference if it's terminal or not
all this means is whether its monosubstituted or disubstituted

it's a double dehydrohalogenation using a very strong base
i think you can start with this information... ;)